48 Hours

Making The Connection

By CBSNews.com staff CBSNews.com staff

June 14, 2001 / 11:32 AM EDT / CBS

Until the last few years, research into spinal cord injuries was seen by many scientists as a frustrating dead end. But with an infusion of funding and an explosion of new discoveries, the field has recently taken off. Many believe that within a few decades, those paralyzed by spinal cord injuries may have a chance to see significant improvement. Below are a few of the most promising leads that researchers are pursuing.

Electrical Stimulation: Researchers at Indiana University and Purdue University are experimenting with low-level electrical stimulation, trying to regenerate spinal cells. Purdue researchers implanted a small battery pack near the spines of paralyzed dogs. The device sent a weak electrical signal (thousandths of a volt) to the site of injury. In about a third of the cases, the dogs improved significantly. A human trial is to begin soon.
Artificial Insulation: Acorda Therapeutics, a company outside New York City, is testing a drug called 4-aminopyridine (4-AP), which may help cure both spinal cord injuries and multiple sclerosis. The drug takes the place of myelin, and plugs leaks in the nerve, allowing electrical charges to be transmitted. The drug is now in human trials involving 90 patients all over the country. Unlike most other treatments for spinal cord injuries, 4-AP appears to work with patients who have been paralyzed for months or years. Others are experimenting with administering a concentrated dose of the drug directly to the spinal cord.
Hormones: Some spinal injury researchers are investigating hormones known as growth factors, which can spur growth of myelin and other spinal tissue. An Israeli company called Proneuron is using growth factors called macrophages, immune cells that promote healing. Macrophages are not found in great numbers in the spinal cord, so Proneuron scientists took them from elsewhere in the body and inject them into the damaged area. In experiments on rats, the treatment worked 70 percent of the time. Several humans have received the treatment so far. One, Melissa Holley, has had a partial return of sensation and movement.
Stem Cells: Researchers in many areas are studying these cells, which make replacement cells for other body parts. Certain kinds of stem cells can create any kind of cell in the body, including spinal cord cells. In an effort to promote regrowth, University of Florida scientists have put these embyronic stem cells into the spinal cords of paralyzed patients. A group of researchers in Massachusetts has tried to grow stem cells in spinal tissue by cultivating them on biodegradable scaffolding. Stem cell research is controversial, however, because abortion foes have protested the use of human tissue taken from embryos.
Pig Cells: At Washington University in St. Louis, researchers have injected millions of pig fetal cells into the spines of two paralyzed people. Researchers hope tht the cells will produce myelin, a substance that insulates nerve cells, and allows them to heal and to send electrical signals. In experiments with mice and rats, some paralyzed animals regained partial use of the hind limbs after treatment.
Peripheral Damage: When damaged, injured peripheral nerves sometimes regenerate. But injured spinal nerves do not. In experiments on rats, a group of researchers at the Massachusetts General Hospital in Boston succeeded in tricking the spinal nerves to regrow. By injuring the peripheral nerve at the same time, they damaged a related spinal nerve, they were able to cause the latter to regenerate. The scientists are now trying to locate the molecules that somehow tell the spinal cells to begin growing.
The Nose Knows: Spinal cord research pioneer Geoffrey Raisman of the National Institute for Medical Research in London is experimenting with specialized olfactory cells known as Olfactory Ensheathing Glia (OEG). These cells are especially adept at regenerating. Raisman injected these OEG cells into the spinal cords of rats. After several months, about half of the rats regained some movement.
Gut Instinct: In experiments on rats, Purdue University researchers have transplanted nerve cells from the gut into injured spinal cords. They have found that these cells will "take," and are now looking into whether they can help restore function and sensation.
Blocking the Blockers: Some spinal cord tissue seems to contain chemicals that stop nerve regeneration. Martin Schwab, a University of Zurich researcher, has identified thesesubstances, which are called neurite inhibitory factors (NIFs). He has gone on to discover an antibody known as IN-1 that can block key nerve-cell growth inhibitors. There are still many questions to be answered, including whether the nerves can regrow properly once they are freed from the NIF bonds.